Decoration of gold and silver nanoparticles by neuroprotective gabapentin drug and studying the release behavior by surface plasmon resonance

Abstract

Epilepsy is a problematic neurological disorder combined with recurrent seizures, and gabapentin is a vital antiepileptic drug proposed for the treatment of many neuropathic pains. However, the bioavailability of this drug decreases with enhancing dose and may alter the central nervous system and induces different side effects. Therefore, design and fabrication of visible-light sensitive nanocarriers for this drug are being demanded in the few past years. Herein, gold and silver nanoparticles are synthesized through the simple Turkevich method and characterized by TEM, DLS, XRD and UV–Vis techniques. The XRD and TEM analyses confirmed formation of the face-centered cubic Au and Ag crystalline phases with 20–30 nm in size. Then, the prepared nanoparticles are used as drug-loadable nanospheres (DLNs) for gabapentin in an aqueous colloidal solution. It is found that the characteristic surface plasmonic resonance (SPR) peaks of the DLNs loaded with gabapentin (DLNs-LG) are strongly dependent on the concentration of the loaded drug. Moreover, the SPR and drug-release behavior of the DLNs-LG are investigated upon three different light sources (red, green, and blue). The obtained results show that the most efficient way to release the maximum amount of drug is to adopt the wavelength of the light source with the SPR peak of the synthesized DLNs-LG. A sensible hypsochromic blue shift is also observed by increasing the irradiation time on the DLNs-LG NPs, establishing the time-dependent nature of the drug-release process. Moreover, the performed numerical calculations exhibit interesting information on the loading and release processes and an equation is finally derived to qualitatively evaluate the amount of the detached drug from DLNs-LG NPs. Furthermore, it is found that the green light is favored for Au NPs; whereas the blue LED source is preferred for Ag NPs to achieve the best release efficiency. The outputs of this study can be useful to understand the influence of light irradiation on the drug-loaded nanoparticles in order to introduce a new method to study drug release/loading mechanisms onto Au and Ag NPs.